GM Vs Animal Insulin

Choices – The Evidence
Evidence from people with diabetes
A little bit of history
Action and duration times of animal and GM ‘human’ insulins
Hypoglycaemia and loss of warnings
‘Dead in Bed Syndrome’
The concerns of patients are justified
Availability of animal insulins in the UK
Changing your insulin
What to do if your consultant refuses to change your insulin
Availability of animal insulin if admitted to hospital
Frequently asked questions
Allergic reactions to insulin


Choices – The Evidence

The NHS has always allowed patients to have an informed choice of treatment before they make their treatment decisions and this includes information about risks and benefits. In recent years, greater emphasis has been placed on informed choice as a result of NHS policy which puts patients at the centre of care and encourages involvement in their treatment decisions so that in the ideal world, patients and their doctors make decisions jointly.

The treatment of diabetes is no exception and therefore people with insulin-requiring diabetes, whether Type 1 or Type 2 diabetes should have an informed choice of insulins and should be given information about risks and benefits.

IDDT has always argued that this should be the case and so if people have a preference for natural pork or beef insulins, whether this is due to adverse reactions to GM synthetic insulins or simply personal preference, then their views should be respected. IDDT advocates the same principles should apply to the newer insulin analogues.

The importance of high quality evidence to inform our decisions
When new drugs, including new insulins, reach the market the research has been in limited numbers of people. Often this early research only involves a highly selected group of people who are not necessarily typical of the general population with a condition who will be using the new drug or insulin. So at this stage, there are many uncertainties about new insulins – are there any adverse effects? Do they suit some categories of patient better than others? Are they superior to their predecessors etc? Is their long-term safety known?

We must also remember that when a new insulin reaches the market, the manufacturers use the media to present it in the best possible light in order to maximise their sales and perhaps they make exaggerated or unsubstantiated claims about its benefits and rarely admit to itd risks or drawbacks. So while it is important that we are aware of new insulins, it is also important to remember that our decisions should be made on the basis of good, high quality, independent research.

The best form of evidence is from good quality reviews, such as Cochrane Reviews, which examine all randomised controlled trials, assess their quality and draw conclusions from this information. Importantly, reviews may identify an absence of evidence and this too can help to inform our choices. For example, if research has not investigated the long-term safety of a type of insulin, then this is an uncertainty and treatment with it has associated risks which may influence our choice. Equally, if research has not compared the complication rates of different insulins, then this too is an unknown and without such information, our choices are not truly informed.


There are three types of insulin:

  • Natural animal insulins – derived from pancreases of pigs or cattle
  • Synthetic ‘human’ insulins – made in a laboratory by genetic modification
  • Insulin analogues – the latest insulin made by genetically modifying GM ‘human’ insulin

Let’s take a look at the evidence now in the public domain:

Human and animal insulins

Rapid-acting insulin analogues

  • Rapid-acting insulin analogues have only minor benefit for the majority of patients.
    Cochrane Review, 2005
  • Rapid-acting insulin analogues are not superior to human insulin for the treatment of Type 2 diabetes.
    The Institute for Quality and Cost Effectiveness in the Health Care Sector – [IQWiG], July 2006
  • Rapid-acting insulin analogues are not superior to human insulin for the treatment of adults with Type 1 diabetes. The benefits for children and adolescents are unclear for lack of data.
    IQWiG, June 2007

Long-acting insulin analogues

  • Long-acting analogue insulins can be used as an option for people with Type 1 diabetes but not for those with type 2 diabetes, except under special circumstances.
    NICE guidance, 2002
  • Long-acting insulin analogues are not listed in Canada for treatment of Type 1 or Type 2 diabetes because they are not superior to NPH human insulin.
    Canadian Expert Drug Advisory Committee [CEDAC], June and Sept 2005
  • Long-acting insulin analogues have only minor benefit, if at all, for the treatment of Type 2 diabetes.
    Cochrane Review, April 2007
  • Intermediate acting versus long acting insulin for Type 1 diabetes mellitus – not enough evidence to draw conclusions on benefits and risks.
    Cochrane Review July 2008
  • No proof that long-acting analogues outperform human insulin in Type 2 diabetes.
    IQWiG March 2009

Details of the above Reviews can be found on our ‘Reviews and Reports’ pages

The conclusions from the present evidence are clear – GM insulins are not superior to their predecessors.

There is no evidence that ‘human’ insulins are superior to animal insulin and it is reasonable to say that there is little evidence that insulin analogues are superior to ‘human’ insulin for the majority of people.

The decision about the choice of insulin should always be made on the basis of individual need, presence of adverse effects or personal preference. However, the importance of individual need and preference becomes very much greater when there is little evidence of superiority of the newer insulins.

For example, if an elderly person living on their own has always used a regime of two injections a day with ‘human’ or animal insulin, changing them to insulin analogues which means at least 4 injections a day can result a reduction in their quality of life, in confusion and even the danger of injecting the wrong insulin at the wrong time.

And what about risks?
The long-term safety of insulin analogues has not been established but it is known that they have the potential for carcinogenic effects with growing evidence of their mitogenic effects [cell multiplication which could lead to tumours]. Insulin analogues and cancer

So there are real grounds for people with diabetes to question whether these risks, however small, are worth taking when insulin analogues have not been demonstrated to be superior to older alternative insulins for which these risks do not appear to be present.

All the Cochrane Reviews of insulin analogues warn that a cautious approach to prescribing them should be adopted because of the lack of evidence of long-term safety, The 2005 International Diabetes Federation Position Statement on insulins, suggests that insulin analogues should only be used in patients where insulin analogues could be expected to help with specific problems.

Exercise your choice
Already 40% of people with diabetes have had their insulin changed to insulin analogues, an unnecessarily change according to the evidence and the newly diagnosed are automatically being treated with analogues. On what basis analogues are being so widely prescribed? From the above evidence of lack of superiority, it can only be on assumptions of benefit not evidence of benefit. This could be as a result of heavy marketing of the analogues as ‘designer’ or ‘modern’ insulins, both of which imply superiority or benefit. It is also worth noting that insulin analogues are the only insulins still in patent and therefore they can be sold at a higher price and greater profit for industry.

Insulin analogues are significantly more expensive than ‘human’ and animal insulins and although the cost does not directly affect individual people in the UK, it does affect the overall NHS costs. Cost is less important than health risks, but Professor Edwin Gale questions whether people with diabetes are getting the best deal. He asks what choice people in the UK would make between treating 150-200 patients with long-acting analogues [rather than human insulin] or for the same cost, employing a full time specialist nurse to improve the education of people with diabetes so that they are better able to self-manage their diabetes.
[Diabetologia (20070 50:1783-1790]

It is important that people with diabetes:

  • are involved in treatment decisions about their health
  • ask questions medications and about their insulin choices
  • ask for the evidence to support any recommendations that are being made, especially if it means changing their present insulin and regime.

Sadly in diabetes the choice of treatment has never truly rested with patients but if the intended discontinuations of some animal and human insulins go ahead, it will not be our doctors that are making our treatment decisions but drug companies. This is unacceptable, harmful and sets a dangerous precedent for healthcare generally.